The present invention relates to a method of recording register marks in a film on which color separation pictures are set, thereby locating the color separation pictures exactly. More particularly, the present invention relates to a method of recording such register marks in the film with the use of a color scanner.
It is known in the art that when color pictures are to be printed, the color separation of the original is carried out so as to produce yellow, magenta, cyan and black color plates, which are printed on the same paper in ink of the respective colors, thereby reproducing the original color pictures.
In such cases, it is necessary to register exactly the color separation plates, and if they are not exactly registered, non-alignment of color occurs in the print, thereby resulting in poor quality.
In order to secure a sharp and clear setting of color pictures in the print without non-alignment of colors, the registering of color separation plates is very important and, as shown in FIG. 15, the common practice is to prepare a transparent lay-out film 4 having a size corresponding to that of the plate to be processed, and provide pins 5 in openings 6 whereby the film is fixed. Then a color separation halftone positive 3 for the first color plate (usually a magenta plate) is adhered to the film 4 in accordance with the lay-out by an adhesive tape. When all the halftone positives 3 are printed, the operation is finished for the first color plate.
Then, a second transparent film 4 is firmly set by reference to the first color plate (i.e., the magenta plate), with the use of the pins 5, and a second color separation halftone positive 3 is printed after it is registered with the magenta halftone positive, thereby finishing the second operation with respect to the second color plate (e.g. cyan plate). Likewise, the printing is finished with respect to the third color (e.g. yellow) and the fourth color (e.g. black plate). When the second to fourth color pictures are registered with the reference first color ones, the cross-shaped register marks 2 can be used to secure the exact registering of color pictures.
The inventor made an invention relating to a method of recording register marks in color scanning for securing an exact registering of color pictures, which is disclosed in Japanese Patent Application Laid-Open No. 54-46602. As shown in FIG. 17, according to this method the cross-shaped register marks 24 are produced by the cross directional linear pictures 25 parallel with the subscanning direction, and the grain directional linear pictures 26 parallel with the main scanning direction, wherein the register marks are positive. In this way the register marks 24 are continuously and exactly recorded in a blank area T.sub.2, i.e., outside the color separation pictures YI, MI, CI and KI.
However, under this previous method the register marks 24 of cross shape are positive throughout all the color separation plates, from which the following disadvantages have resulted:
Because of non-alignment, the line widths are likely to appear to be thicker or thinner than the actual widths; however, these apparent dimensional changes are apt to be overlooked, and an allowance for registering below the actual line widths of the register marks is often permitted. As a result, the operators must continuously pay utmost attention to the registering work, which is a heavy burden for them, and leads to inefficiency.